Supply System And Method For Providing Electric Energy, Oxygen Depleted Air And Water As Well And Aircraft Having Such A Supply System

ABSTRACT

A supply system for providing at least oxygen depleted air and water in a vehicle includes a catalytic converter, at least one hydrogen supply means, at least one air supply means, at least one outlet for oxygen depleted air, and a control unit coupled with the catalytic converter. The catalytic converter is couplable with the hydrogen supply means and is adapted for producing water under consumption of hydrogen from the at least one hydrogen supply means and oxygen. The catalytic converter is further couplable with the at least one air supply means for additionally producing oxygen depleted air. Further, the control unit is adapted for selectively operating the catalytic converter based on a demand of water and oxygen depleted air.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.14/808,273, filed on Jul. 24, 2015, the disclosure of which isincorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to a supply system and a method for providingelectric energy, oxygen depleted air and water as well as to an aircrafthaving such a supply system.

BACKGROUND OF THE INVENTION

Today's aircraft are often equipped with separate systems for emergencypower supply and cargo fire suppression. For a so-called “total engineflame out” (TEFO) situation or the loss of a main electrical powersupply, a ram air turbine for providing emergency power is designated.Ram air turbines are capable for providing sufficient power when thespeed of the impinging ram air is sufficient. However, this may becritical in a phase close to touchdown during the landing phase of theaircraft.

For extinguishing or suppression of a fire in a cargo compartment of anaircraft, Halon fire extinguishers were often used. Due to adverseeffects of Halon for the ozone layer and as Halon will be limited byauthorities, a replacement of Halon is necessary.

In civil aviation, potable water systems are well-known, which use onboard water storage tanks for providing the quantity of water used inflight by passengers and crew and lavatories and galleys. It is known togenerate potable water on board by means of fuel cells under consumptionof hydrogen and oxygen. However, this kind of water generation isdirectly coupled with the generation of electrical power. Hence, waterwill only be produced if there is a demand for electric power.

In case air is used as an oxidant, fuel cells deplete the oxygen contentof the air when generating water. If the remaining oxygen content in thecathode air is reduced to approximately 12%, this oxygen depleted air isusable for suppressing fire in case of a fire event on board or be usedfor fuel tank inerting or increasing safety in the fuel system. Thedepletion of oxygen is directly coupled with the demand for electricpower and the stoichiometry in the fuel cell.

BRIEF SUMMARY OF THE INVENTION

Consequently, an aspect of the invention may provide a supply system forproviding at least oxygen depleted air and water, which is capable toindependently generate oxygen depleted air and optionally water

A supply system for providing at least oxygen depleted air and water isproposed, the system comprising a catalytic converter, at least onehydrogen supply means, at least one air supply means, at least oneoutlet for oxygen depleted air, and a control unit coupled with thecatalytic converter. The catalytic converter is couplable with thehydrogen supply means, the catalytic converter is adapted for producingwater under consumption of hydrogen from the at least one hydrogensupply means and oxygen, the catalytic converter is couplable with theat least one air supply means for additionally producing oxygen depletedair, and the control unit is adapted for selectively operating thecatalytic converter based on a demand of water and oxygen depleted air.

The catalytic converter is adapted for providing water in gaseous orliquid form and oxygen depleted air when supplied with air from the atleast one air supply means and hydrogen from the at least one hydrogensupply means. The converter comprises a catalyst, i.e. a chemicalsubstance that increases the rate of the intended chemical reactionwithout being consumed. In particular, the catalyst of the catalyticconverter allows to lower the process temperature, thereby reducing thedemand for cooling power. For example, the catalyst may be realized as aplatinum powder coating inside a converter housing.

The hydrogen supply means may be a hydrogen port in a hydrogen supplysystem, a section of a hydrogen duct, a storage tank or any other meanscapable of supplying hydrogen or a hydrogen containing gas to the fuelcell. In this regard, the hydrogen does not necessarily have to be purehydrogen. Instead, it may also be generated from a fuel processor, whichreforms an ordinary aircraft fuel into hydrogen enriched gas for fuelcells.

In analogy, the air supply means may be any suitable means for providingair, such as a ram air inlet, a bleed air port of a turbojet engine, aport integrated into or coupled with a recirculation duct of anenvironmental control system in an aircraft, a cargo compartmentextraction valve, or any other means.

The system may further comprise a dedicated outlet for oxygen depletedair, which may be coupled with several active components, or the systemmay include one or more outlets for oxygen depleted air at the differentactive components.

The catalytic converter is adapted for providing water in gaseous orliquid form and oxygen depleted air when supplied with air from the atleast one air inlet and hydrogen from the at least one hydrogen supplymeans. Depending on the temperature necessary for conducting thechemical reaction between hydrogen from the at least one hydrogen supplymeans and an oxidant, the generated water may comprise a certaintemperature and, consequently, a certain aggregation state.

Consequently, the direct relation between electric power demand, demandfor oxygen depleted air and the stoichiometry in a fuel cell stack andwater production in a fuel cell system may be eliminated through the useof a catalytic converter capable of providing water and, if desired,oxygen depleted air.

In an advantageous embodiment, the supply system further comprises afuel cell, which is couplable with the hydrogen supply means. The fuelcell is adapted for producing water and electric energy throughconducting a fuel cell process under consumption of hydrogen from the atleast one hydrogen supply means and oxygen. Further, the control unit isadditionally adapted for selectively operating the fuel cell based on ademand of water, oxygen depleted air and electric energy.

The fuel cell may be realized by means of a single fuel cell, a fuelcell stack having a plurality of interconnected fuel cells or anarrangement of fuel cells or fuel cell stacks in a series or parallelconnection. The fuel cell is couplable with the at least one hydrogensupply means, such that hydrogen is supplyable to the fuel cell ondemand. The necessary oxidant may be provided in the form of oxygen, airor any other oxygen containing gas, which allows to supply a sufficientflow of oxygen to the fuel cell.

The fuel cell itself may be of any suitable type, which may include alow temperature, a medium temperature or a high temperature fuel celltype that produces electricity and heat as well as water, which arisesat a cathode side of the fuel cell. For the use in vehicles, the fuelcell may preferably include proton exchange membrane fuel cells, alsoknown as polymer electrolyte membrane fuel cells.

Hence, the fuel cell may be operated when water and electric power arerequired at the same time. The catalytic converter may produce water onits own, without having to deliver electric power. Also, oxygen depletedair, water and electric power may be provided at the same time when thefuel cell is supplied with air and hydrogen. The fuel cell and thecatalytic converter may produce water at the same time or separately atdifferent times. In particular, the fuel cell is only operated when ademand for electrical power has to be met.

A still further advantageous embodiment comprises an oxygen supply meansfor providing substantially pure oxygen to the at least one fuel cell.This means that the fuel cell may be supplied with pure oxygen, suchthat only water is produced in the fuel cell, without oxygen depletedair being generated. However, it is preferred to provide pure oxygenonly to one of the installed active components, i.e. the fuel cell, suchthat a demand for oxygen depleted air may be met by at least the otheractive component.

In case the fuel cell is supplied with pure oxygen, the system accordingto the invention may be used as an emergency power supply unit, which iscompletely independent from any other component in the vehicle, as longas the oxygen and hydrogen supply is maintained.

Still further, the control unit is adapted for operating the catalyticconverter and the fuel cell at the same time for producing at leastwater and electric energy. This may reduce the total weight of thesystem according to the invention, as for meeting the water demandarising in the vehicle both active components may be used, which doesnot require the dimensioning of one or both of them to meet the demandalone.

In an advantageous embodiment, the fuel cell is couplable with the atleast one air supply means for additionally producing oxygen depletedair. For a quick supply of oxygen depleted air, e.g. in case of a demandfor fire suppression, the fuel cell may also be couplable with the atleast one air supply means, allowing to increase the total flow rate ofoxygen depleted air. Depending on the resulting flow rate it may bepossible to also provide a fire knock down function. However, the fuelcell may only provide oxygen depleted air when the electrical power,which is generated during the fuel cell process, can be provided to anelectrical load. It may be preferred that the outlets for oxygendepleted air at the fuel cell and the catalytic converter aresegregated. If a combination of emergency power generation andgeneration of oxygen depleted air is required, the fuel cell may beoperated under consumption of pure oxygen, which may be necessary e.g.in a TEFO case. A segregation of the respective outlet of the fuel celland the catalytic converter prevents that in the above case pure oxygenreaches the catalytic converter, which would otherwise hinder thegeneration of oxygen depleted air, may lead to an overheat in thecatalytic converter or the introduction of oxygen into the space thatneeds to be inerted, i.e. leading to a fire acceleration.

It is preferred that the system comprises at least one of a waterseparator and a condenser, thereby enabling the reliable separation ofliquid water or the condensation of water vapor during the operation ofthe system. A condenser may be required when water occurs in gaseousform, for example downstream the catalytic converter, depending on itsoperating temperature, or downstream a fuel cell operating at elevatedtemperatures.

For fire suppression during normal operation of the vehicle, which maybe an aircraft, the air supply means comprises a bleed air line from aturbojet engine. It goes without saying that the bleed air supplied froma bleed air line should be pre-cooled for preventing damages to the fuelcell or the catalytic converter. The supply of bleed air is reliable andfurthermore comprises a steady and adjustable pressure level.

In a still further embodiment, the catalytic converter comprises ahousing, which is arranged in an air duct, and wherein the catalyticconverter is adapted for condensing water generated in the catalyticconverter at the housing. The power required for condensation is clearlyreduced. Exemplarily, the catalytic converter may be arranged in a ramair duct, in particular when the vehicle is an aircraft, such that ramair having a low temperature impinges the housing of the catalyticconverter and is able to compensate the latent evaporation heat.

Arranging the catalytic converter into an air duct, in which a constantair flow occurs, allows cooling the catalytic converter without asophisticated cooling system. Additionally, the air duct, be it a ramair duct, a duct for leading exhaust air of a compartment or cooling airfrom another device, allows a heat exchanger being integrated into theair duct, which heat exchanger may be coupled with a cooling system forthe fuel cell, if used in the system according to the invention, whichclearly simplifies the overall cooling system for the active componentsin the system.

It goes without saying that the catalytic converter, the fuel cell andpower electronics for converting the electrical voltage and current fromthe fuel cell may comprise any kind of cooling system, be it an air orcooling liquid based cooling system, as an open or a closed coolingloop, which cooling systems may be combined or realized as separatecooling systems.

For clearly increasing the process of catalytic conversion, thecatalytic converter may comprise a turbo machine having a compressor anda turbine. The catalytic converter may then be adapted for providing thecatalytic conversion in a position between the compressor and theturbine, such that compressed air is fed into the catalytic converter,after which the products generated in the catalytic converter flowthrough the turbine. For example, in case the fuel cell system is usedin an aircraft, a situation may arise in which the aircraft is on groundwith doors closed and engines not running, such that no bleed air isavailable for a fire knock down function. However, a substitute may begenerated by means of a small, preferably electrically operated turbomachine, which also makes use of the temperature raise of the catalyticconversion for decreasing the required power for the compressor due tothe mechanical power created by the turbine, thereby leading to a greatefficiency of the catalytic converter in this operation case. Further,due to the expansion in the turbine, the oxygen depleted air flow ispre-cooled.

In another advantageous embodiment, an air inlet of the catalyticconverter is coupled with an exhaust air outlet of a compartment in thevehicle and the at least one outlet for oxygen depleted air is coupledwith an air inlet of the compartment. Fire suppression in thiscompartment is clearly improved through recirculating air from thecompartment into an air inlet of the catalytic converter, which reducesthe oxygen content through the catalytic conversion and lets the oxygendepleted air flow back into the respective compartment. Using such arecirculation improves the speed of oxygen depletion in the respectivecompartment and may, if the capacity of the catalytic converter issufficient, provide for a fire knock-down. However, the catalyticconverter requires an additional source of air for maintaining thecatalytic conversion process, if the oxygen content in the respectivecompartment is below a certain level.

The system may further be adapted for selectively switching between anair supply and oxygen supply to the fuel cell based on the demand onwater, oxygen depleted air and electrical power through appropriatelyswitching respective supply valves.

The invention further relates to a method for providing at least oxygendepleted air and water in an aircraft, the method comprising operating acatalytic converter for producing water under consumption of hydrogenfrom at least one hydrogen supply means couplable with a hydrogen supplymeans of the catalytic converter and coupling at least one air supplymeans with the catalytic converter and operating the catalytic converterfor additionally producing oxygen depleted air wherein based on a demandof water and oxygen depleted air.

Further, the method may comprise recirculating exhaust air from acompartment in the vehicle to an air inlet of the catalytic converter.

The invention further relates to an aircraft having such a supplysystem.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics, advantages and application options of thepresent invention are disclosed in the following description of theexemplary embodiments in the figures. All the described and/orillustrated characteristics per se and in any combination form thesubject of the invention, even irrespective of their composition in theindividual claims or their interrelationships. Furthermore, identical orsimilar components in the figures have the same reference characters.

FIG. 1 shows a system for providing oxygen depleted air, water andelectric energy in a first exemplary embodiment having a supply of pureoxygen to a fuel cell and an air supply to a catalytic converter.

FIG. 2 shows another embodiment having a catalytic converter with anintegrated turbo machine.

FIG. 3 shows a further embodiment with an air supply to the fuel cell.

FIG. 4 shows a still further embodiment with a cargo air supply to thecatalytic converter.

FIG. 5 shows another embodiment with a catalytic converter with anintegrated turbo machine and cargo air supply to the converter.

FIG. 6 shows another, simplified embodiment with only a catalyticconverter.

DETAILED DESCRIPTION

FIG. 1 shows a first exemplary embodiment of a supply system 2 forproviding oxygen depleted air and water, the system 2 comprising acatalytic converter 4, a hydrogen supply means 6 having a hydrogenreservoir 8 and a plurality of valves 10, a first air supply means 12realized as a ram air channel, a second air supply means 14 realized asa bleed air line as well as an oxygen supply means 16 comprising anoxygen reservoir 18 as well as a series of valves 20.

Further, a fuel cell 22 realized as a fuel cell stack is present, whichfuel cell 22 is couplable with the oxygen supply means 16 and thehydrogen supply means 6. Through conducting a fuel cell process, thefuel cell 22 produces electrical energy and water. Hydrogen from thehydrogen supply means 6 flows into an anode inlet 24 and residualhydrogen exits an anode outlet 26, from where it may be conveyed to theanode inlet 24 or to a hydrogen supply line 28, which will be furtherdescribed below. Hydrogen ions reach the cathode side and react withoxygen flowing into the fuel cell 22 through a cathode inlet 28 to formwater flowing off a cathode outlet 30.

Exemplarily, a water separator 32 is coupled with the cathode outlet 30and is adapted to separate water from residual gas flowing from thecathode outlet 30. Water accumulating in the water separator 32 may befed back to an injecting means 34 upstream of the cathode inlet 28 inorder to provide a humidification of the oxygen flowing into the cathodeinlet 28 for improving the operation of the fuel cell 22.

The catalytic converter 4 is coupled with the hydrogen supply means 6through a first hydrogen supply line 34 and is furthermore couplablewith the hydrogen supply line 28 as described above. Both hydrogensupply lines 28 and 34 provide hydrogen to the catalytic converter 4which is supplied with air either from the first air supply means 12 orthe second air supply means 14. It goes without saying that both airsupply means 12 and 14 may also be used at the same time while it shouldbe prevented that air from one of the air supply means enters the otherair supply means driven by a pressure difference. The catalyticconverter 4 conducts the reaction between oxygen from the air andhydrogen in order to provide oxygen depleted air (“ODA”) at an oxygendepleted air outlet 36. Water vapor that arises from the chemicalreaction may be drawn away by the surrounding airflow.

Consequently, the system 2 is able to provide oxygen depleted air, waterand electrical energy basically independent from any other devices andnearly requires a source of oxygen and hydrogen for conducting the fuelcell process and air and hydrogen for conducting the catalytic reaction.

For cooling the fuel cell 22, a cooling circuit 38 is present, whichextends from a cooler 40 mounted in the first air supply means 12 to thefuel cell 22 and back. For conveying a cooling fluid flowing inside thiscooling circuit 38, a pump 42 as well as a buffering tank 44 arepresent.

The system 2 further comprises a control unit 46, which is coupled withthe fuel cell 22 and the catalytic converter 4 for controlling theiroperations. It goes without saying that also the plurality of valves 10or 20 are controllable through the control unit 46, which is thenresponsible for selectively operating one or both of the fuel cell 22and the catalytic converter 4 for providing oxygen depleted air, waterand electrical energy based on the respective demands.

In FIG. 2, a system 48 is shown, which slightly differs from system 2 ofFIG. 1. The main difference lies in converter 50, which is a combinedturbo machine having a catalytic converter, which is able to provide alarge mass flow of oxygen depleted air suitable for a fire know downprocess. A compressor 52 thereby compresses ram air from the air supplymeans 12 and expands the flow in a turbine 54. Between compressor 52 andturbine 54, a plurality of catalytic converters 56 may be arranged aswell as downstream of the turbine 54. After providing the knock downfunction, the operation of the turbo machine may be interrupted, suchthat a lower mass flow for fire suppression may be initiated.

In FIG. 3, a system 58 is shown, which is simplified compared to system2 and system 48 from FIGS. 1 and 2. For example, fuel cell 22 isprovided with hydrogen from hydrogen supply means 6, while the oxygensupply is realized through a third air supply means 60 coupled with thecathode inlet 28. Consequently, not only water occurs at the cathodeoutlet 30 but also oxygen depleted air, which may be recirculatedthrough a recirculation duct 62 to the cathode inlet 28 or may be fed toa catalytic converter 4 as a fourth air supply means 64. Consequently,oxygen depleted air from the fourth air supply means 64 is even morereduced in its oxygen content while the first air supply means 12 may bereduced to a mere supply of cooling air.

The catalytic converter 66 comprises an additional function in the formof a condenser, which is able to provide condensed water at a wateroutlet 68, which may be fed through a float drain valve 70 to adedicated water supply outlet 72.

FIG. 4 shows a system 74 for providing oxygen depleted air, water andelectric energy, which system 74 is based on system 2 shown in FIG. 1.Here, the catalytic converter 4 is supplied with air from the first airsupply means 12 and, at the same time, is supplied with air from a fifthair supply means 76 that draws off used cargo air by means of aconveying device 78, which provides the cargo air through a safetycatalyst 80 into the catalytic converter 4. Oxygen depleted air thatexits the oxygen depleted air outlet 36 may be fed to a cargocompartment, which provides the used cargo air for the fifth air supplymeans 76. By this process, the oxygen content may be even more reducedinside the cargo compartment, which leads to a clearly improved firesuppression.

In FIG. 5, a system 82 for providing oxygen depleted air, water andelectrical energy is shown, which is based on the system 48 of FIG. 2.Here, the first air supply means 12 is slightly modified and named sixthair supply means 84, which is provided with cargo air instead of ramair, but is still realized as a channel or duct for housing thecatalytic converter 50 as well as the cooler 40 for fuel cell 22. Byfeeding the oxygen depleted air arising at the oxygen depleted airoutlet 36 into the cargo compartment that provides the cargo air, astill further improved oxygen depletion may be accomplished.

In this regard it goes without saying that, as shown in FIG. 6, a system86 for providing oxygen depleted air and water may be possible withoutthe use of a fuel cell 22. The use for fire suppression or fire knockdown through a catalytic converter may clearly improve the efficiency ofthe aircraft in terms of weight and fuel consumption as alternativesolutions for providing an inert gas or water comprise a clearly higherweight.

In addition, it should be pointed out that “comprising” does not excludeother elements or steps, and “a” or “an” does not exclude a pluralnumber. Furthermore, it should be pointed out that characteristics orsteps which have been described with reference to one of the aboveexemplary embodiments can also be used in combination with othercharacteristics or steps of other exemplary embodiments described above.Reference characters in the claims are not to be interpreted aslimitations.

While at least one exemplary embodiment of the present invention(s) isdisclosed herein, it should be understood that modifications,substitutions and alternatives may be apparent to one of ordinary skillin the art and can be made without departing from the scope of thisdisclosure. This disclosure is intended to cover any adaptations orvariations of the exemplary embodiment(s). In addition, in thisdisclosure, the terms “comprise” or “comprising” do not exclude otherelements or steps, the terms “a” or “one” do not exclude a pluralnumber, and the term “or” means either or both. Furthermore,characteristics or steps which have been described may also be used incombination with other characteristics or steps and in any order unlessthe disclosure or context suggests otherwise. This disclosure herebyincorporates by reference the complete disclosure of any patent orapplication from which it claims benefit or priority.

1. A supply system for providing at least oxygen depleted air and waterin a vehicle, the system comprising: a fuel cell; an independentcatalytic converter; at least one hydrogen supply means; at least oneair supply means; at least one outlet for oxygen depleted air; and acontrol unit coupled with the catalytic converter, wherein the fuel celland the independent catalytic converter are couplable with the hydrogensupply means, wherein the fuel cell is adapted for producing water andelectric energy through conducting a fuel cell process under consumptionof hydrogen from the at least one hydrogen supply means and oxygen;wherein the independent catalytic converter is adapted for producingwater under consumption of hydrogen from the at least one hydrogensupply means and oxygen, wherein the independent catalytic converter iscouplable with the at least one air supply means for additionallyproducing oxygen depleted air, and wherein the control unit is adaptedfor selectively operating one or both of the fuel cell and theindependent catalytic converter based on a demand for water, oxygendepleted air, and electrical energy.
 2. The supply system of claim 1,further comprising an oxygen supply means for providing oxygen to thefuel cell in the absence of an air supply.
 3. The supply system of claim1, wherein the control unit is adapted for operating the independentcatalytic converter and the fuel cell at the same time for producing atleast water and electric energy.
 4. The supply system of claim 1,wherein the fuel cell is couplable with the at least one air supplymeans for additionally producing oxygen depleted air.
 5. The supplysystem of claim 1, further comprising at least one of a water separatorand a condenser.
 6. The supply system of claim 1, wherein the at leastone air supply means comprises a bleed air line from a turbojet engine.7. The supply system of claim 1, wherein the independent catalyticconverter comprises a housing, which is arranged in an air channel, andwherein the independent catalytic converter is adapted for condensingwater generated in the catalytic converter at the housing.
 8. The supplysystem of claim 1, wherein an air inlet of the independent catalyticconverter is coupled with an exhaust air outlet of a compartment in thevehicle, and wherein the at least one outlet for oxygen depleted air iscoupled with an air inlet of the compartment.
 9. An aircraft having asupply system comprising: a fuel cell; an independent catalyticconverter; at least one hydrogen supply means; at least one air supplymeans; at least one outlet for oxygen depleted air; and a control unitcoupled with the independent catalytic converter, wherein the fuel celland the independent catalytic converter are couplable with the hydrogensupply means, wherein the fuel cell is adapted for producing water andelectric energy through conducting a fuel cell process under consumptionof hydrogen from the at least one hydrogen supply means and oxygen,wherein the independent catalytic converter is adapted for producingwater under consumption of hydrogen from the at least one hydrogensupply means and oxygen, wherein the independent catalytic converter iscouplable with the at least one air supply means for additionallyproducing oxygen depleted air, and wherein the control unit is adaptedfor selectively operating one or both of the fuel cell and theindependent catalytic converter based on a demand for water, oxygendepleted air, and electrical energy.